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[McTraveller]

Yes, it was a question of "where are the missing reaction forces" and they are in the Poynting vectors.

EDIT: I think the stack exchange conversations are missing a beat though - they keep using the F = dP/dt formulation, and I think they may actually be better off using F = dE/dx, which seems to be more applicable to "static" situations where nothing is moving but there are definitely spatial gradients in energy fields.

EDIT 2: Hrm. I'm still struggling with this actually. The Poynting vector only generates a force if it's changing... and in a static situation (even with "static" currents) it's not changing. Maybe I need more coffee...it's also in the wrong direction... :thinking:

[McTraveller]

New big question: Do all the cosmological models that drive the need for MOND or dark matter or whatever, does that already account for the mass equivalent of all the EM radiation that is occupying every part of space?

That is, if you have a beam of photons/light ray from a star, there is some "traditional" energy density (therefore mass density) in every volume of space.  Do they account for that in the models about galaxy rotation that claim to need some correction? I can't recall seeing any papers that adjust the data for general energy density in space.

[Il Palazzo]

It's negligibly tiny. You need a few times more mass than baryonic mass, while the MW emits on the order of 10E37 Watts. That's something like 10E20 kg of mass equivalent radiated every second. If we assume it's all produced in the centre, and needs 50k years to leave the premises of the Galaxy, then it'd be an equivalent of 100 Suns of mass within the entire Galaxy.
Since it all scales with flux density as well as photon energy, farther sources are even more negligible, including the microwave background (at this epoch). The dark matter justification coming from observations of the microwave background rather than galaxy dynamics does take radiation density into account in the form of the radiation component of the Friedmann equations.

[EuchreJack]

Hm, but what if we gave each stellar and galactic body a buddy?

[McTraveller]

Wow, is it really that small?  Huh.  I mean I guess the sun itself, at 10³⁰ kg emitting 10²⁶ W (~10⁹ kg) is only emitting 10^-21 its mass every second. I guess that is a "trivial" amount...

[Magmacube_tr]

Where is Old Zealand?

WHERE IS IT!?

[Il Palazzo]

In Viking land. Or at least used to be. Going by the tone of your question it might have sailed away and is now missing.

[dragdeler]

Oldest zealand is probably spelled seeland or zeeland.

[Magmacube_tr]

In Viking land. Or at least used to be. Going by the tone of your question it might have sailed away and is now missing.

Fuck, they sailed off before I could find them, again.

[hector13]

I was under impression it was a wee island off the coast of the Netherlands, but that’s a guess

[Flying Teasets]

 

[EuchreJack]

In Viking land. Or at least used to be. Going by the tone of your question it might have sailed away and is now missing.

Fuck, they sailed off before I could find them, again.

Princess Zeeland is in another castle.

[King Zultan]

You don't find Zeeland, Zeeland finds you.

[scriver]

Yeah there's one zeeland in Dutchland and one sealand in Denmark. They're both ilses. The one in Denmark is fairly big and hosts their capital. Both names mean "island-land".

[Scoops Novel]

Why weren't pyromaniacs a bigger problem in the past?